UNE MED BIOCHEM UNIT 3 TEST QUESTIONS WITH ACCURATE ANSWERS A+

UNE MED BIOCHEM UNIT 3 TEST QUESTIONS WITH ACCURATE ANSWERS A+ An increase in the ratio of insulin to glucagon will increase the activity of which of the following enzymes (+ indicates activity is increased; - indicates activity is not increased by insulin)? - ANS-(-) hormone sensisitve lipase (+) acetyl-CoA carboxylase (+PFK2) (+) Gycogen synthase when insulin is elevated fed state pathways will be persistent. This will include the activation of acetylCoA carboxylase will be activated in fatty acid synthesis. PFK2 in gycolysis (breakdown of glucose) and glycogen synthase will also be active converting excess glucose to glycogen to be stores for later. hormone sensitive lipase is active in lipolysis --> in the fasting state Which of the following is the regulatory enzyme for fatty acid synthesis? Citrate lyase Malic enzyme Fatty acid synthase Acetyl-CoA carboxylase - ANS-Acetyl-CoA carboxylase the regulatory step in fatty acid syntehsis is the synthesis of malonyl-coA by acetyl-CoA carboxylase. This reaction uses CO2 and bioton to add carbon to cystolic acteyl-COA Fatty Acid synthase is used in Beta oxidation! Insulin stimulates lipogenesis through several mechanisms. Which of the following is not an insulin stimulated process that enhances lipogenesis? Decreased activity of the pyruvate dehydrogenase complex Decreased levels of cAMP Increased glucose transport into the cells Increased activity of acetyl-CoA carboxylase - ANS-Decreased activity of the pyruvate dehydrogenase complex Insulin stimulates PDC--> the enzyme that converts pyruvate to Acetyl-CoA which is active during glycolysis (High glucose, high insulin) Acetyl-CoA Carboxylase- the rate limiting step of fatty acid synthesis(lipogenesis). insulin would increase this. Increased glucose transport is likely happening with insulin cAMP- in the glucagon pathway, insulin would inhibit this An individual consumes a large meal consisting of a cheeseburger and fries. Which of the following intermediates is shuttled out of the TCA cycle to be used as a substrate for fatty acid synthesis? Isocitrate Oxaloacetate Citrate Malate - ANS-Citrate The tricarboxylate transporter is responsible for moving citrate from the mitochondria to the cytosol for fatty acid synthesis. isocitrate is downstream of citrate. oxaloacetate is a precursor to citrate in the TCA cycle . Citrate is cleaved to make OAA and acetyl-CoA Malate--> OAA via malate dehydrogenase in TCA cyle An increase in the ratio of insulin to glucagon leads to which of the following metabolic shifts? 1. Acetyl-CoA carboxylase will become dephosphorylated and active 2. Cytosolic levels of malonyl-CoA will decrease 3. Hormone sensitive lipase will become dephosphorylated and active 4. VLDL synthesis will decrease - ANS-Acetyl-CoA carboxylase will become dephosphorylated and active When insulin is elevated fed state pathways will be persistent. This will include the activation of acetylCoA carboxylase through dephosphorylation. cytosolic malonyl-CoA will increase Hormone sensitive lipase is a fasted state , activated by glucagon and epinephrine. this will NOT be active...